The DOK-T apparatus was developed and constructed at DSP-IEP-SAS for project PROGNOZ-8 and started very successful series of particle spectrometers of DOK-type with passive cooling of the detectors.
The device consists of two parts - the detector head and the electronic box.
The detector head contains two parallel oriented solid state semiconductor detectors, one of them is exposed to particle flux directly, another one is equipped with a mylar foil.
As the foil stops the heavier ions with much higher efficiency than the lightweight electrons,
this pair of detectors allows to some extent to distiguish the ion and electron fraction of the particle flux.
A limiting issue of the particle spectroscopy with the semiconductor detectors is the noise of the detectors. As the noise is proportional to the temperature, the DOK-T uses passive cooling based on the efficient radiation of the heat from the sensor head which is located at the shadow side of the spacecraft. A low temperature performance has been provided by a thermal separation of the sensor head by a multilayer insulation (MLI) inserted between the sensor head and the electronic box. Thus about –50°C of the detector temperature was achieved during the experiment.